This is a study of the impact of aerobic exercise conditioning on blood pressure variability (BPV) responses to psychological and physical stressors. It derives from a model which holds that autonomic control of the heart serves a buffering or inhibitory function over oscillations in blood pressure, which recent research in vascular biology and dynamics suggests may have pathogenic effects on the endothelium, in the case of atherogenesis, and on plaque stability, in the case of catastrophic cardiac events.